> Same for thermostats.

I've lost count of how many times I opened the windows and then went out without turning off the heating causing it to run at full blast trying to fight the winter outside.

A window sensor + smart thermostat + Home Assistant solved that problem and the system has been reliably running for 2 years now. I can now open & close the windows at will knowing that the heating will adapt around that and not waste energy. Note that there is no UI, no voice assistants, not even screens involved. It just works in the background.

Do I agree with the current gimmicky consumer-grade implementation of a "smart home" and controlling everything with your phone/voice assistant? No, that's stupid. But it doesn't mean the idea of a smart home should be dismissed - there are ways to actually make it useful and pleasant if you are willing to spend some time and/or money.

When I go away for two weeks in the winter, I'd also like my lights to turn on and off to simulate my home being occupied for security purposes. A simple switch isn't going to cut it.

I use simple smart switches for that. I can use my iPad to switch the lights on and off manually or they can be automated. It does require some “smart home” components but the switches are simple and cheap. i always hated trying to get the mechanical timer switches setup correctly.

I don’t go in for full integration of smart home features into appliances and such. Using smart switches gives me enough “smartness” without to much risk from a system in flux.

Right. For that, you need a timer, which you can also get at Home Depot for a few dollars. What else you got?

The timer is something you can leave on all the time. If you don't come home before dark some day, you still want the lights to go on.

A simple timer plugged into a wall outlet will. We've had those for decades.